Trocar assembly

ABSTRACT

A trocar for use in surgical procedures including a cannula for maintaining a sealed working channel in a body wall and an obturator which creates the working channel through the body wall while protecting patients and medical personnel from harm is disclosed. A cannula converter which can be employed with the trocar to enable a surgeon to use surgical instruments having a smaller outer diameter than the inner diameter of the cannula without deflating a body cavity is further disclosed. A site stabilizer which can be used with the trocar to prevent the cannula from being inadvertently withdrawn from the body cavity during a surgical procedure is also disclosed.

This is a divisional of application Ser. No. 08/189,318, filed on Jan.31, 1994 now U.S. Pat. No. 5,538,509.

FIELD OF THE INVENTION

The invention relates generally to surgical instruments and moreparticularly to trocars for use in surgical procedures.

BACKGROUND OF THE INVENTION

Medical science has long sought ways to minimize the dangers and traumainherent in invasive surgical procedures. To this end, surgicaltechniques and instruments have been developed which, among otherthings, reduce the size of the incisions required to perform varioussurgical procedures. These techniques and instruments have beenremarkably successful. Indeed, surgical procedures which only a fewyears ago would require an incision six or seven inches in length aretoday being performed through incisions which are less than one inch inlength.

Trocars are one type of surgical instrument which have significantlycontributed to these advances. In general, trocars are sharp, pointedsurgical instruments which can be used to create and maintain small,hole-like incisions in a body cavity. Surgical instruments, includingminiaturized optical devices, can be inserted through these smallincisions and manipulated to perform surgical procedures within the bodycavity without ever exposing the patient's internal organs or structuresto the outside environment. Thus, by enabling the creation andmaintenance of small working holes within a patient's body wall,conventional trocars have greatly contributed to the reduction in sizeof the incisions required to perform surgical procedures and reduced therelated complications.

Conventional trocars generally include an obturator and a cannula. Anobturator is a sharp, nail-like structure for penetrating a body wall tocreate a working channel into the body cavity. A cannula is a tube-likestructure which can be inserted into the incision made by the obturatorto maintain the working channel even after the obturator is removed. Inthe typical scenario, the obturator and cannula are assembled into asingle unit (i.e., by inserting the obturator into the cannula) and thenused to puncture the body wall. The obturator can then be carefullywithdrawn from the cannula without removing the cannula from the bodywall. Surgical instruments can be inserted through this cannula toperform an entire surgical procedure within the body cavity as mentionedabove.

While conventional trocars plainly have many benefits, they also presentsignificant hazards to both patients and medical personnel. For example,a patient is placed at risk of serious injury by the manner in which thetrocar is employed. Specifically, in order to insert a trocar into apatient, a physician must overcome the resistance of the patient's bodywall by exerting a significant amount of pressure on the trocar. Whenthe obturator tip passes beyond the body wall the resistance suddenlyreduces significantly. Thus, unless the physician immediately stopsapplying force, the trocar can move rapidly forward and possiblypuncture or tear delicate internal organs. Since, the drop in resistanceoften occurs very suddenly, it can be very difficult to remove the forcebefore injury occurs.

Medical personnel and patients are also placed at risk by the sharp tipsof conventional trocars. Specifically, the sharp trocars make it veryeasy for medical personnel to inadvertently cut themselves or otherwisepuncture their skin or gloves when using a conventional trocar. Not onlyare such accidental wounds painful, but they can also transfer the bloodof the patient to the injured medical personnel or vice versa. With theincreasingly widespread threat of HIV, the well-publicized AIDs virus,and other communicable diseases, the danger of accidental bloodexchanges provides a clear danger to anyone involved with a conventionaltrocar. This is especially true when medical personnel are injured in asurgical setting since the patient's blood will likely be present whenthe accidental wound occurs. An accidental wound to a medical workercould, therefore, easily result in accidental blood exchanges betweenthe injured party and the patient.

In addition to the serious risks detailed above, conventional trocarscause medical personnel many other problems. For instance, in manysurgical procedures involving trocars, the body cavity is inflated witha non-toxic gas before the trocar is employed to create a working"pocket" or volume within the patient and to prevent the trocar frompenetrating internal organs during insertion. For example, in anappendectomy, a patient's abdomen is first inflated with gas through averess needle. The obturator is then used to place cannulas in variouslocations about the inflated abdomen for performing the procedure. Onesuch cannula would typically be used to pass a small camera and lightinto the body cavity so a surgeon could view the operating area withinthe patient. Other cannulas would be used to pass surgical instrumentsinto the cavity and remove tissue such as the appendix from the patient.

It is very important to maintain the abdomen of the patient in aninflated state throughout the procedure. To this end, conventionalcannulas are often provided with sealing flap valves or the like whichprevent gas from escaping from the patient's abdomen after the obturatoris withdrawn. However, these sealing flap valves do not prevent gasleakage when a surgical instrument having a diameter which is smallerthan the diameter of the cannula is employed. Instead, gas can easilypass through the gap between the inner wall of the cannula and the outersurface of the surgical instrument and deflate the work area. To preventdeflation of this type from occurring, physicians have often beenrequired to utilize only those instruments whose dimensions closelymatch those of the cannula. This requirement inherently limits thesurgeon's freedom of choice in selecting instruments for a procedure.Thus, while a certain instrument might be preferred by a physician, thephysician might nonetheless be forced to use a less preferred (andpossibly less effective) tool to perform a procedure to avoid deflatinga body cavity.

Another problem conventional trocars present lies in the ease with whichconventional cannulas can be inadvertently withdrawn from the workingchannel. Conventional cannulas typically include a smooth outer walldesigned to facilitate insertion of the device through a body wall. Thesmooth surface of the cannula insures that the tissue surrounding theincision does not suffer excessive trauma when the cannula is passedthrough the body wall. Unfortunately, it also insures that the cannulacan be withdrawn from the incision as smoothly and easily as it wasinserted. This lack of resistance to withdrawal can easily result in theinadvertent withdrawal or removal of the cannula when an obturator orother surgical instrument is withdrawn. Inadvertent removals can createmultiple problems, including deflation of the body cavity, splatteringof body fluids, loss of time, and unnecessary trauma to the body tissuesurrounding the working channel from the resulting multiple removals andinsertions of the cannula.

OBJECTS OF THE INVENTION

It is, therefore, a general object of the present invention to providean improved trocar for use in surgical procedures which protects bothpatients and medical personnel from injury. More specifically, it is anobject of the invention to provide an improved trocar which will helpprevent the inadvertent penetration of a patient's internal organsduring insertion. It is a related object to provide an obturator whosesharp tip can only be exposed when the obturator is attached to acannula.

It is another object of the present invention to provide a trocarassembly which does not limit a surgeon's choice of surgical instrumentsto those instruments having a specific diameter. It is a related objectto provide a trocar assembly which can be used with surgical instrumentsof different diameters without deflating a body cavity and withoutreplacing the trocar cannula, which was used for insertion, with acannula of a different size.

It is yet another object of the invention to provide a trocar assemblywhich can be easily inserted into a body wall but which cannot beinadvertently withdrawn from the patient.

SUMMARY OF THE INVENTION

The present invention accomplishes these objectives and overcomes thedrawbacks of the prior art by providing a trocar for use in surgicalprocedures which includes a cannula for maintaining a sealed workingchannel in a body wall and an obturator which protects patients andmedical personnel from harm. In addition, the present invention providesa cannula converter for use with the trocar cannula which enablessurgeons to use surgical instruments having smaller diameters than thetrocar cannula without deflating a body cavity. Finally, the inventionalso provides a site stabilizer for use with the trocar which preventsthe inadvertent withdrawal of the cannula from the patient's body wallduring a surgical procedure.

As previously mentioned, the present invention provides an obturatorwhich protects patients and medical personnel from harm. Morespecifically, the present invention provides an obturator which includesa shaft having a side wall defining a substantially hollow interior withsubstantially open, proximal and distal ends. The shaft includes aninterior wall which runs within its hollow interior from one open end tothe other such that the interior wall and the side wall combine todefine multiple open-ended chambers. One end of the shaft is formed intoa piercing tip to enable the obturator to penetrate a body wall. Ahandle is attached to the end of the shaft opposite the piercing tip.

In order to protect patients and medical personnel from injury, theobturator is further provided with safety shield members which areslidably disposed within the open-ended chambers of the shaft. Thesesafety shield members extend the length of the shaft from the piercingtip into the handle chamber where they abut a spring. This spring biasesthe safety shield members into an extended position wherein the safetyshield members surround the cutting edges of the piercing tip. Thus,when the obturator is pressed against a body wall, the safety shieldmembers will compress the spring as they retract into the shaft. Whenthe obturator penetrates the wall, the safety members will quickly moveforward under the force of the spring to again cover the tip and protectthe patient from harm.

Optionally, the obturator is further provided with a unique lockingmechanism for controlling the translation of the safety shield members.This locking mechanism prevents the safety shield members from leavingthe extended position when the obturator is disengaged from the cannula.In other words, the safety shield members can only be retracted when theobturator is attached to a cannula. When the obturator is disengagedfrom the cannula, the locking mechanism will insure that the safetyshield members cover the piercing tip thereby preventing inadvertentinjuries. Once the obturator engages a cannula, the locking mechanismwill permit the members to retract. However, the locking mechanism willonly permit the safety shield members to retract once. Consequently,after the safety shield members return to the extended position, theywill be unable to retract unless the obturator is detached andre-attached to a cannula to restart the procedure. Thus, the lockingmechanism prevents the safety shield members from inadvertentlyretracting after penetrating a body cavity and thereby helps preventinadvertent penetration of internal organs.

In accordance with another aspect of the invention, a cannula converteris provided which permits surgical instruments having a diameter whichis smaller than the diameter of the included cannula to be used withoutdeflating an inflated body cavity and without replacing the cannula,which was used for insertion, with a cannula having a smaller interiordiameter. More specifically, the cannula converter includes a housinghaving a first portion and a second portion. The first and secondportions of the housing each define an opening adapted to receivesurgical instruments. The openings of the first and second portionscommunicate through a channel which permits surgical instruments to passthrough the converter. The housing includes a seal for sealably engagingthese surgical instruments. In addition, the converter is provided withan attachment assembly for attaching the housing to the trocar cannulasuch that surgical instruments can be passed through the converter andthe trocar cannula for performing surgical procedures. In an optionalembodiment, the housing of the converter is further provided with a lipor rim for sealably engaging the cannula to help prevent deflation ofthe body cavity.

In accordance with yet another aspect of the invention, the trocar isalso provided with a site stabilizer for preventing an attached trocarcannula from being inadvertently withdrawn from a body wall. The sitestabilizer includes a stem which defines a channel for receiving thetrocar cannula and which includes external threads for engaging the bodywall of a patient. A head having a top portion and a bottom portion isconnected to the stem. Both the top and the bottom portions of the headdefine an opening which is aligned with the channel defined by the stemfor receiving the trocar cannula. The bottom portion of the headincludes a camming structure. A handle which is slidably disposed atleast partially within the head operatively engages the cammingstructure. A gripping device disposed adjacent the handle is actuatedbetween a release position for receiving and releasing the trocarcannula and a grip position for securing and gripping the trocar cannulaas the handle moves along the ramp structure. In an optional embodiment,the site stabilizer is further provided with a seal disposed within thehead and positioned for receiving the cannula to help prevent deflationof the body cavity and to provide drag on the cannula during insertion.

It will be appreciated that any of the above-described components (i.e.,the obturator, cannula, cannula converter or site stabilizer) can beused apart from the other components without departing from theinvention. However, the trocar assembly, namely the obturator, cannula,cannula converter and site stabilizer, can also be used as a kit toovercome the above described problems associated with conventionaltrocars.

These and other features and advantages of the invention will be morereadily apparent upon reading the following description of the preferredembodiment of the invention and upon reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a left, front perspective view of a trocar constructed inaccordance with the teachings of the present invention;

FIG. 2 is a front side view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a back side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is an exploded view thereof illustrating the obturator separatedfrom the cannula;

FIG. 9 is an exploded view of the obturator illustrating theconstruction of the obturator handle and the locking mechanism;

FIG. 10 is an exploded view of the safety shield members and obturatorshaft illustrating the construction of the safety shield members;

FIG. 10A is a top plan view of the shaft of the obturator taken alonglines 10A--10A of FIG. 10;

FIG. 10B is a bottom plan view of the shaft of the obturator taken alonglines 10B--10B of FIG. 10;

FIG. 10C is a bottom plan view similar to FIG. 10B but illustrating thesafety shield members disposed in the shaft of the obturator;

FIG. 10D is a partial, enlarged front side view of the piercing tip ofthe obturator illustrating the safety shield members in the retractedposition;

FIG. 11 is a fragmentary, front side view of the trocar with its safetyshield members retracted;

FIG. 12 is a partial cross-sectional view of the trocar handle takenalong lines 12--12 of FIG. 6 illustrating the locking mechanism in thereleased position;

FIG. 12A is a cross-sectional view similar to FIG. 12, but illustratingthe locking mechanism when the safety shield members are retracted;

FIG. 13 is a cross-sectional view taken along lines 13--13 of FIG. 12;

FIG. 14 is a cross-sectional view similar to FIG. 12 but illustratingthe locking mechanism in the locked position;

FIG. 15 is a cross-sectional view similar to FIG. 12 but illustratingthe locking mechanism in a second locked position.

FIG. 16 is a left, front perspective view of a cannula converterconstructed in accordance with the teachings of the present invention;

FIG. 17 is a left, front perspective view of the cannula converterattached to the cannula;

FIG. 18 is a top plan view of the cannula converter;

FIG. 19 is a bottom plan view of the cannula converter;

FIG. 20 is a front side view of the cannula converter;

FIG. 21 is a left side view of the cannula converter;

FIG. 22 is a cross-sectional view of the cannula converter taken alonglines 22--22 of FIG. 20;

FIG. 23 is a cross-sectional view of the cannula converter taken alonglines 23--23 of FIG. 20;

FIG. 24 is a cross-sectional view of the cannula converter taken alonglines 24--24 of FIG. 18;

FIG. 25 is an exploded view of the cannula converter illustrating theinteraction of the seal housing and the attachment housing.

FIG. 26 is a front perspective view of a site stabilizer constructed inaccordance with the teachings of the present invention;

FIG. 27 is a left, front perspective view of the site stabilizerattached to the trocar;

FIG. 28 is a top plan view of the site stabilizer;

FIG. 29 is a bottom plan view of the site stabilizer;

FIG. 30 is a partial cross-sectional front side view of the sitestabilizer;

FIG. 31 is a cross-sectional view of the site stabilizer taken alonglines 31--31 of FIG. 30;

FIG. 32 is a cross-sectional view of the site stabilizer taken alonglines 32--32 of FIG. 30;

FIG. 33 is an exploded view of the site stabilizer;

FIG. 34 is a partial cross-sectional view of the site stabilizerattached to the trocar illustrating the site stabilizer in the lockposition;

FIG. 35 is a partial cross-sectional view of the site stabilizerattached to the trocar illustrating the site stabilizer in the releaseposition;

FIG. 36 is an enlarged, cross-sectional view of the site stabilizerhandle interacting with the camming structure taken along lines 36--36of FIG. 31 illustrating the handle in the release position; and

FIG. 37 is an enlarged, cross-sectional view similar to FIG. 36 butillustrating the handle in the lock position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A trocar 10 constructed in accordance with the teachings of the presentinvention is shown generally in FIG. 1. The trocar 10 is specificallyconstructed to create and maintain small working channels through apatient's body wall. To this end, the trocar 10 comprises two detachablecomponents, namely, an obturator 12 and a cannula 130. As best seen inFIG. 8, the obturator 12 is the portion of the trocar 10 which actuallycreates the channel in the body wall. As explained in greater detailbelow, the obturator 12 is equipped with a sharp piercing tip 16attached to a shaft 18 which terminates in a handle 20. The tip 16,shaft 18, and handle 20 combine to facilitate the insertion of thetrocar 10 into a patient. The cannula 130 is the component of the trocar10 which maintains the working channel for insertion of surgicalinstruments and the like during a given procedure. As discussed below,the cannula 130 includes an open-ended tube 132 which communicates witha handle 134 to provide a channel for receiving surgical instruments.

During insertion into a patient, the obturator 12 is first inserted intothe cannula 130 such that the trocar 10 forms a single assembly asillustrated in FIG. 2. When assembled in this manner, the piercing tip16 of the obturator 12 extends slightly beyond the open-ended tube 132of the cannula 130. The trocar 10 can then be inserted into a patientsuch that the obturator 12 and the attached cannula 130 pierce the bodywall of the patient. After insertion, the obturator 12 can be removedfrom the cannula 130 and the cannula 130 can be left in position tomaintain a working channel for passing surgical instruments and the likeinto and out of the patient.

As previously mentioned, the obturator 12 includes a handle 20 whichenables a physician to comfortably grip and insert a trocar 10 includingthe obturator 12 into a patient. Although other sizes and shapes mightalso be appropriate, the handle 20 preferably has a rectangular shapewhich can be easily gripped by a surgeon. Even more preferably, the top22 of the handle 20 is contoured to provide a smooth, curved surfacewithout sharp edges or points as illustrated in FIGS. 1-6. This smooth,curved top 22 enables a physician or surgeon to insert a trocar 10employing the obturator 12 by applying force to the obturator handle 20with the palm of their hand without discomfort.

As best seen in FIG. 8, the obturator handle 20 is preferablyconstructed to matingly engage the cannula handle 134. The obturatorhandle 20 and the cannula handle 134 thus combine to form a singlehandpiece 14 when the trocar 10 is assembled in a single assembly asillustrated in FIG. 2. This handpiece 14 is preferably sized to becomfortably gripped by a physician. To this end, the bottom 136 of thecannula handle 134 preferably has a smooth curved shape as illustratedin FIGS. 3-5 and 7. The smooth curved shape of the bottom 136 of thecannula handle 134 provides a comfortable surface for the physician'sfingers during insertion of the trocar 10. The combination of the curvedtop 22 of the obturator handle 20 and the curved bottom 136 of thecannula handle 134 results in a handpiece 14 which a surgeon cancomfortably hold and use with a single hand. Although the abovedescribed handpiece construction is preferred, it will be appreciated bythose skilled in the art that handpieces having other shapes, sizes andconfigurations can also be employed without departing from theinvention.

As illustrated in FIG. 12, the trocar 10 is preferably provided with anattachment assembly 24 for removably attaching the obturator handle 20to the cannula handle 134. The attachment assembly 24 insures that thetrocar 10 remains assembled as a single unit when inserted through abody wall. As illustrated in FIG. 15, the preferred attachment assembly24 comprises two oppositely disposed pivotable buttons 27, 29 includingtabbed arms 26, 28. The pivotable buttons 27, 29 and the tabbed arms 26,28 are connected such that they pivot as a single unit. The pivotablebuttons 27, 29 are pivotally mounted upon posts 25, 31 contained withina handle chamber 21 defined by the obturator handle 20. The buttons 27,29 are pivotable between two extreme positions, a lock position whereinthe tabbed arms 26, 28 are disposed at their most outward position forengaging notches 30, 32 in the cannula handle 134, and a releaseposition wherein the tabbed arms 26, 28 are disposed at their mostinward position free of the notches 30, 32. A spring 34 disposedadjacent to the tabbed arms 26, 28 biases the buttons 27, 29 into thelock position. Thus, when the trocar 10 is assembled as a single unit,the tabbed arms 26, 28 engage the notches 30, 32 and prevent theobturator 12 from inadvertently separating from the cannula 130.However, as illustrated in FIGS. 2, 4, 8 and 9 the buttons 27, 29 arepositioned outside the assembled handpiece 14 within recesses 33, 35 inthe exterior of the obturator handle 20 and cannula handle 134,respectively. Consequently, a user can overcome the biasing force of thebutton spring 34 by applying an inwardly directed force to the buttons27, 29 and thus releasing the tabbed arms 26, 28 from the notches 30, 32to separate the obturator 12 from the cannula 64.

In order to assist the attachment of the obturator 12 and the cannula130, the cannula handle 134 is further provided with a pair ofoppositely disposed lead-in ramps 116. As illustrated in FIG. 15, theselead-in ramps 116 provide smooth, inclined surfaces which encourage thetabbed arms 26, 28 of the pivotable buttons 27, 29 of the attachmentassembly 24 to pass into the cannula handle 134 where they engagenotches 30, 32, respectively.

In accordance with an aspect of the invention, the obturator 12 isprovided with a shaft 18 for penetrating the body wall of a patient. Asillustrated in FIGS. 10 and 10A, the shaft 18 preferably includes acylindrical side wall 19 which defines a substantially hollow interior.Further, as illustrated in FIG. 10A, the shaft 18 is preferably providedwith three interior walls 40, 42, 44 which divide the substantiallyhollow interior of the shaft 18 into three separate chambers 46, 48, 50.Both the walls 40, 42, 44 and the chambers 46, 48, 50 preferably extendthe length of the shaft 18 from the proximal to the distal end. Inaddition, the opposite ends of the shaft 18 are open. Consequently, thechambers 46, 48, 50 are open-ended and, thus, provide passagescompletely through the shaft's interior. Since the proximal end of theopen-ended shaft 18 is mounted within the handle chamber 21 asillustrated in FIG. 12, the chambers 46, 48, 50 defined by the side wall19 and the interior walls 40, 42, 44 of the shaft 18 communicate withthe interior of the handle chamber 21.

As illustrated in FIG. 10, the end of the obturator shaft 18 oppositethe obturator handle 20 is provided with a sharp piercing tip 16. Thispiercing tip 16 is preferably formed by sharpening the side 19 andinterior walls 40, 42, 44 of the shaft 18 into a piercing point 17.Thus, in the preferred embodiment, the piercing tip 16 is integrallyformed with the obturator shaft 18. In addition, since the piercing tip16 is preferably formed by sharpening the side wall 19 and the interiorwalls 40, 42, 44 of the shaft 18, the preferred piercing tip 16comprises three angularly positioned blades 41, 43, 45 configured in asubstantially pyramidal shape as illustrated in FIGS. 7 and 10B. As bestseen in FIG. 10B, each of these blades 41, 43, 45 includes a first endand a second end. The first ends of the blades 41, 43, 45 are joined toform the piercing point 17 and the second ends of the blades 41, 43, 45engage the side wall 19 of the shaft 18. Further, to facilitatepenetration of the body wall each blade 41, 43, 45 includes twooppositely angled side portions 41A, 41B, 43A, 43B, 45A, 45B whichintersect to form sharp cutting edges 41C, 43C, 45C. The oppositelyangled side portions 41A, 41B, 43A, 43B, 45A, 45B and the cutting edges41C, 43C, 45C, are thus located between the first and second ends of theblades 41, 43, 45. As illustrated in FIGS. 10B, 10C and 10D, the blades41, 43, 45 are positioned such that each pair of adjacent blades definean opening therebetween which communicates with one of the open-endedchambers 46, 48, 50.

It will, of course, be appreciated by those skilled in the art thatalthough the preferred embodiment employs three interior walls 40, 42,44 defining three chambers 46, 48, 50, other amounts of interior walls(i.e. 1, 2, 4, etc.) could also be employed without departing from theinvention. Similarly, although the preferred embodiment employs apiercing tip 16 formed by sharpening the shaft's side 19 and interiorwalls 40, 42, 44 into a point 17, separate piercing tips affixed to theshaft 18 could be substituted without departing from the invention.Also, although the piercing tip 16 has been described as pyramidal inshape, other shapes could also be employed. Piercing tips having othershapes and configurations might be required, for example, if other thanthree interior walls and three interior chambers are employed. Finally,although the obturator shaft 18 has been illustrated as having asubstantially circular cross-section it will be appreciated that shaftshaving cross-section of other shapes such as triangular, oval,hexagonal, etc. might likewise be appropriate. However, it will beappreciated by those skilled in the art that the use of shafts havingnon-circular cross-sections and configurations may require similaradjustments to the shapes and configuration of other components of thetrocar 10 and, potentially, to other surgical instruments for use withthe trocar 10.

In accordance with another aspect of the invention, the obturator 12 isprovided with retractable safety shield members 52, 54, 56 slidablydisposed within the open-ended chambers 46, 48, 50 defined by theinterior walls 40, 42, 44 of the shaft 18. As illustrated in FIG. 10,these safety shield members 52, 54, 56 each include a tip 58, 60, 62, ashaft 64, 66, 68, and a tabbed end 70, 72, 74, respectively. The tabbedend 70, 72, 74 of each member 52, 54, 56 is preferably received by anattachment block 76 which binds the safety shield members 52, 54, 56together such that the shield members move simultaneously. To this end,the attachment block 76 is provided with receiving slots 78, 80, 82,each of which receive a tabbed end 70, 72, 74 of a member 52, 54, 56.Preferably, the tabbed ends 70, 72, 74 slide into the retaining slots78, 80, 82. However, alternate assembly methods employing adhesives,mechanical fasteners such as screws, or other techniques could also beused to permanently fasten the safety shield members 52, 54, 56 to theattachment block 76 without departing from the invention.

After the safety shield members 52, 54, 56 are secured to the attachmentblock 76, the members 52, 54, 56 are inserted into the chambers 46, 48,50 of the obturator shaft 18 as illustrated in FIGS. 9 and 10C. Inaccordance with an important aspect of the invention, the individualshafts 64, 66, 68 of the safety shield members 52, 54, 56, which arepreferably all substantially equal in length, are longer than theobturator shaft 18 itself. Consequently, even though the attachmentblock prevents the safety shield members 52, 54, 56 from passingcompletely into the shaft's chambers 46, 48, 50, the tips 58, 60, 62 ofthe members extend beyond the point 17 of the piercing tip 16 of theobturator 12. Thus, the safety shield members 52, 54, 56 combine tocover the piercing tip 16 and prevent the tip 16 from inadvertentlycutting, piercing, or otherwise injuring an individual.

As illustrated in FIGS. 10B-10C, the individual blades 41, 43, 45 of thepiercing tip 16 are blunted into triangular lands 51, 53, 55 near theouter wall 19 of the shaft 18. These lands 51, 53, 55 are preferablyfree of sharp edges. As best seen in FIG. 10C, the blunting of theblades 41, 43, 45 into lands 51, 53, 55, respectively, insures that thesharp, cutting surfaces of blades 41, 43, 45 do not extend beyond thesafety shield members 52, 54, 56 when the members 52, 54, 56 are in theextended position. In other words, the blunting of the outer portions ofthe blades 41, 43, 45 insures that the sharp cutting edges 41C, 43C, 45Cof these blades 41, 43, 45 are no longer than the corresponding sides ofthe tips 58, 60, 62 of the safety shield members 52, 54, 56 (i.e., fromthe piercing point 17 to the individual triangular lands 51, 53, 55).

As previously mentioned, the chambers 46, 48, 50 of the obturator shaft18 communicate with the handle chamber 21. Thus, when the safety shieldmembers 52, 54, 56 are inserted into the chambers 46, 48, 50, theattachment block 76 is disposed within the handle chamber 21. Asillustrated in FIG. 9, when assembled with the attachment block 76 thetabbed ends 70, 72, 74 of the shield members 52, 54, 56 combine to forma circular gripping structure 92. This circular gripping structure 92,like the attachment block 76 is disposed within the handle chamber 21.

In order to control the movement of the slidably disposed safety shieldmembers 52, 54, 56, the obturator 10 is further provided with a shieldspring 90 as shown in FIG. 9. The shield spring 90 surrounds and gripsthe circular gripping structure 92 formed by the tabbed ends 70, 72, 74of the shield members 52, 54, 56. Further, the shield spring 90 isdisposed within the handle chamber 21 between the attachment block 76and the interior of the obturator handle's top 22. As illustrated inFIGS. 11 and 12, the top 22 of the obturator handle 20 is provided withinwardly directed projections 94 which fix the position of the spring90.

The shield spring 90 biases the safety shield members 52, 54, 56distally towards the extended position wherein the shield memberscombine to cover the piercing tip 16. Thus, in order to move the safetyshield members 52, 54, 56 into the retracted position illustrated inFIGS. 10D and 11, one must exert a force sufficient to overcome thebiasing force of the shield spring 90 upon the shield members. Since theshield members 52, 54, 56 compress the spring 90 as they move towardsthe retracted position, the shield spring 90 will cause the shieldmembers 52, 54, 56 to quickly move distally into the extended positionto once again cover the piercing tip 16 as soon as this overcoming forceis removed.

For example, when using the trocar 10 a physician will grip theassembled handpiece 14 and press the tips 58, 60, 62 of the safetyshield members 52, 54, 56 against the body of the patient. When thephysician exerts sufficient force to overcome the biasing force of theshield spring 90, the shield spring 90 will compress and the safetyshield members 52, 54, 56 will retract into the obturator shaft 18 asillustrated in FIGS. 10D and 11. The retraction of the safety shieldmembers 52, 54, 56 exposes the piercing point 17 and the sharpenedblades 41, 43, 45 of the piercing tip 16 which, consequently, contactthe patient's flesh. The piercing tip 16 then pierces the patient's bodywall and, with continued pressure from the physician, passes completelyinto the patient's body.

It will be appreciated by those skilled in the art that the patient'sbody wall provides significant resistance to this penetration. Thus, inorder to create an incision with the trocar 10, the physician must applya similarly significant amount of force. It will also be appreciated bythose skilled in the art that the resistance of the body wall willsuddenly decrease by a substantial amount when the piercing tip 16passes through the wall. Since the physician will likely be applying asignificant amount of force to the trocar 10 at the instant theresistant drops, the sharp piercing tip 16 can potentially rush forwardand injure the patient's internal organs. In order to avoid any suchinjury, it is imperative that the safety shield members 52, 54, 56quickly return to the extended position to cover the piercing tip 16.

As shown in FIGS. 2, 3 and 10D, the tips 58, 60, 62 of the safety shieldmembers 52, 54, 56 are beveled preferably to each include at least onesurface which is inclined at the same angle as the blades 41, 43, 45 ofthe piercing tip 16 such that the tips 58, 60, 62 and the blades alignwhen the safety shield members 52, 54, 56 are in the retracted positionas illustrated in FIGS. 10D and 11. In this position, the tips 58, 60,62 of the safety shield members 52, 54, 56 form the sides of thepyramidal piercing tip 16 thereby creating a smooth piercing structurefor pushing the flesh surrounding the incision aside and enabling theobturator shaft 18 and cannula tube 132 to easily pass into the patientwithout unnecessarily traumatizing the surrounding flesh.

To this end, each of the tips 58, 60, 62 of the safety shield members52, 54, 56 include a central beveled portion 58A, 60A, 62A, two sideportions 58B, 58C, 60B, 60C, 62B, 62C disposed on opposite sides of thecentral beveled portion 58A, 60A, 62A, and a blunted tip portion 58D,60D, 62D as shown in FIG. 10C. The central beveled portions 58A, 60A,62A each provide a large, smooth surface for pushing a patient's tissueaside with minimal trauma when the trocar 10 is inserted through a bodywall. The oppositely disposed side portions 58B, 58C, 60B, 60C, 62B,62C, align with the oppositely angled side portions 41A, 41B, 43A, 43B,45A, 45B of the obturator shaft's blades 41, 43, 45 in the retractedposition to prevent the patient's tissue from entering the open-endedchambers 46, 48, 50 during insertion. Finally, the blunted tip portions58D, 60D, 62D provide a flat surface which will not easily cut orpuncture tissue or internal organs to enhance the protective function ofthe safety shield members 52, 54, 56 during use. This construction ofthe tips 58, 60, 62 of the safety shield members 52, 54, 56 minimizesthe amount of travel required of the safety shield members 52, 54, 56from the extended to the retracted positions and vice versa. Morespecifically, the beveled construction of the 58, 60, 62 tips insuresthat the blades 41, 43, 45 are exposed for cutting and penetrating abody wall after only a short proximal movement of the safety shieldmembers 52, 54, 56. This short travel distance from the extendedposition to the retracted position likewise insures that the safetyshield members only travel a similarly short distance from the retractedto the extended position thereby minimizing the deployment time of thesafety shield members 52, 54, 56 and reducing the risk of injury tointernal organs during insertion of the trocar 10.

As illustrated in FIGS. 10B and 10D, portions 61, 63, 65 of the sidewall 19 of the obturator shaft 18 are preferably beveled atsubstantially the same angle as the tips 58, 60, 62 of the safety shieldmembers 52, 54, 56. Thus, when the safety shield members 52, 54, 56 arein the retracted position, these beveled portions 61, 63, 65 of the sidewall 19 align with the beveled surfaces of the tips 58, 60, 62 of theshield members 52, 54, 56 to provide a smooth transition between thepiercing tip 16 and the obturator shaft 18 thereby minimizing trauma tothe patient's flesh during insertion. Preferably, the beveled portions61, 63, 65 of the obturator shaft 18 are formed when the side wall 19and inner walls 40, 42, 44 are sharpened to form the piercing tip 16.

As previously mentioned, the shield spring 90 causes the shield members52, 54, 56 to deploy as soon as the force causing their retraction isremoved. Thus, as soon as the sharp tip 17 and blades 41, 43, 45 of thepiercing tip 16 pass through the patient's body wall, the beveled tips58, 60, 62 of the safety shield members 52, 54, 56 will encounter lessresistance and begin to return to their extended position. Moreover, thepyramidal shape of the obturator tip 16 insures that the patient's fleshis penetrated from the center outward. In other words, the piercingpoint 17 of the piercing tip 16 will first penetrate the body wallfollowed by the blades 41, 43, 45 and shield members in ever wideningcircles until the obturator shaft 18 and, preferably, the attachedcannula 130 pass into the body cavity. Since the safety shield members52, 54, 56 are mounted within the obturator shaft 18, the members willpenetrate the body wall a short time before the shaft 18 and cannulatube 132. Consequently, the safety shield members 52, 54, 56 will beginto return to the extended position before the trocar 10 begins to moveinto the patient's body cavity thereby insuring that the piercing tip 16is covered before injury to internal organs or other structures canoccur.

It will be appreciated by those skilled in the art that the shieldspring 90 must be chosen such that the spring 90 compresses and thesafety shield members 52, 54, 56 retract before the patient's flesh isbruised, damaged or torn by the tips 58, 60, 62 of the shield members52, 54, 56. On the other hand, the spring 90 should not be too easilycompressed or inadvertent exposure of the piercing tip 16 could occur.Springs which generate spring forces between 0.3 lbs. and 1.6 lbs.should compress before any damage is done to the patient's tissue andyet require sufficient force to avoid inadvertent piercing tipexposures. Consequently, springs which generate spring forces between0.3 lbs. and 1.6 lbs. are preferred in this role.

It should be noted, however, that trocars having different diameterswill displace different amounts of tissue during penetration.Specifically, trocars having large diameters will displace more tissuethan trocars having small diameters. As a result, trocars having largerdiameters will require springs 90 which generate more force than trocarswith small diameters. Thus, in the most preferred embodiments, a trocar10 having a 5 mm diameter will employ a spring 90 which generates springforces of approximately 0.3 lbs. when the shield members are fullyextended and spring forces of approximately 1.0 lbs. when the shieldmembers are fully retracted, and a trocar 10 having a diameter of 10 mm,11 mm or 12 mm will employ springs 90 which generate spring forces ofapproximately 1.0 lbs. when the shield members are fully extended andspring forces of approximately 1.5 lbs. when the shield members arefully retracted. It will be appreciated that all of these preferredspring forces fall within the general preferred range of 0.3 lbs and 1.6lbs. noted above.

In order to provide the physician with information concerning theposition of the safety shield members 52, 54, 56, the trocar 10 isfurther provided with an indicator 77. As illustrated in FIG. 9, theindicator 77 preferably comprises a projection which is integrallyformed with the attachment block 76 for movement therewith. Thisindicator 77 is received by an opening 15 in the obturator handle 20.Consequently, as illustrated in FIG. 2, the position of the indicator 77can be easily viewed by a surgeon or physician employing the device 10.As illustrated in FIG. 2, when the safety shield members 52, 54, 56 arein their extended position (i.e. their distal or forwardmost position),the attachment block 76 and, thus, the indicator 77 are similarly intheir forwardmost or distal positions. When, however, the safety shieldmembers 52, 54, 56 are retracted as in FIGS. 10D and 11, the attachmentblock 76 and its connected indicator 77 also move to their proximal orrearward positions. By observing the relative position of the indicator77 within the opening 15, the physician will thus be able to identifythe state of deployment of the shield members 52, 54, 56.

The ability to identify the position of the shield members 52, 54, 56can be important because, as explained in detail below, the safetyshield members 52, 54, 56 can be locked in their extended position. Whenthis occurs, the physician cannot cause the members 52, 54, 56 toretract regardless of the force the physician exerts on the trocar 10.If a physician were unable to easily determine the position of thesafety shield members 52, 54, 56 the physician might exert excessiveforce in an attempt to force the shielded tip 16 through the patient'sbody wall. This could result in unnecessary trauma to the patient'sflesh. Such trauma should not occur with the inventive trocar 10 becausea physician will be able to see that the members 52, 54, 56 are notretracting before exerting excessive force.

In addition, as explained above, the safety shield members 52, 54, 56should begin to return to the extended position before the cannula 130enters the patient's body cavity. The physician should be able todiscern this distal or forward motion of the shield members 52, 54, 56by viewing the indicator and, thus, be forewarned that total penetrationis imminent. Consequently, the physician will have an opportunity todecrease the applied pressure before the trocar 10 totally pierces thebody wall to avoid forcing the blunted tips 58, 60, 62 of the safetyshield members 52, 54, 56 against internal organs.

As illustrated in FIG. 4, the back side of the obturator handle 20preferably is not provided with an indicator. Accordingly, although theobturator handle 20 and cannula handle 134 can be assembled into asingle handpiece in either of two orientations (i.e. in the positionillustrated in FIG. 1 or with the obturator 12 rotated 180° with respectto the cannula 130), it is preferable that the physician orient theobturator and cannula handles 20, 134 such that the indicator 77 is mostvisible to the physician during use. Nonetheless, it will be appreciatedby those skilled in the art that a second indicator could be placed onthe back side of the obturator handle 20 such that an indicator appearson both sides of the handle 20 to avoid these concerns with orientationwithout departing from the claimed invention.

In accordance with another aspect of the invention, the obturator 12 ispreferably provided with a locking mechanism 100 for controlling thetranslation of the safety shield members 52, 54, 56. As illustrated inFIGS. 9 and 12, the locking mechanism 100, which is disposed within theobturator handle chamber 21, includes a first spring 102 attached to theattachment block 76 for movement therewith, a second spring 104operatively engaging the first spring 102, a stop 106 attached to theinterior of the obturator handle 20 and having a stop projection 106A,and a translatable arm 108 operatively engaging the second spring 104.

As best seen in FIG. 13, the first spring 102 has an L-shape with afirst leg 101 of the "L" engaging the attachment block 76 adjacent theindicator 77 and the other leg 103 disposed substantiallyperpendicularly to the first leg 101. Although the entire first spring102 is carried by and travels with the attachment block 76, the secondleg 103 of the first spring 102 also translates between a lock position(illustrated in FIG. 14) and a release position (illustrated in FIG. 12)in a direction transverse to the movement of the attachment block 76. Tothis end, the second leg 103 of the first spring 102 is biased to theleft in FIG. 12A. When in the lock position, the second leg 103 of thefirst spring 102 prevents the safety shield members 52, 54, 56 fromretracting into the handle chamber 21 by abutting the stop 106.

As shown in FIG. 12, this stop 106 is a projection affixed to theinterior of the obturator handle 20. When the first spring 102 is in thelock position, its second leg 103 is below and abuts the stop 106thereby preventing the attachment block 76 from moving rearward ordistally as illustrated in FIG. 14. Consequently, the safety shieldmembers 52, 54, 56 cannot retract into the shaft 18 to expose thepiercing tip 16. On the other hand, when the first spring 102 isdisplaced into the release position illustrated in FIGS. 12 and 13, theattachment block 76 and the safety shield members 52, 54, 56 can freelyretract because the spring 102 will pass around (as shown in FIG. 12A),rather than abut, the stop 106 (as shown in FIG. 14).

In order to control the movement of the first spring 102 between thelock and release positions, the locking mechanism 100 is furtherprovided with a second spring 104. As shown in FIG. 12, the secondspring 104 is disposed in a plane which is substantially perpendicularto the second leg 103 of the first spring 102. Unlike the first spring102, however, the second spring 104 is not secured to the attachmentblock 76. Instead, the second spring 104 is secured within the obturatorhandle 20. Further, the second spring 104 is biased for movement in twodirections, namely, towards the stop projection 106A disposed upon stop106 (i.e. upwards in FIG. 12) and away from the first spring 102 (i.e.to the left in FIG. 12).

As best seen in FIG. 15, the translatable arm 108 is pivotally mountedupon a post 110 adjacent the second spring 104. The translatable arm 108includes a head 112 which receives the post 110 and an elongated leg114. As illustrated in FIG. 15, the elongated leg 114 passes through anopening in the obturator handle 20 to engage the cannula handle 134 whenthe trocar 10 is assembled into a single unit. Since the second spring104 is biased away from the first spring 102, the second spring 104exerts an outward force upon the translatable arm 108 which moves thearm 108 to the left position illustrated in FIG. 15 whenever theobturator 12 is separated from the cannula 130.

When the biasing force of the second spring 104 moves the translatablearm to the left (i.e. whenever the obturator handle 20 is separated fromthe cannula handle 134), the leg 105 of the second spring 104 likewisemoves to the left. Before the obturator handle 20 and the cannula handle134 are separated, the first spring 102 can be in one of two positions,the lock position or the release position. If the safety shield members52, 54, 56 have been previously retracted, the leg 103 of the firstspring 102 will be in the lock position (i.e. below the stop 106 andabove the second spring 104) as illustrated in FIG. 14. If so, theleftward movement of the leg 105 of the second spring 104 will noteffect the position of the first spring 102. However, the leg 105 of thesecond spring 104 will slide past the first spring 102 and snap upwardinto contact with the stop projection 106A of stop 106 such that the leg105 of the second spring 104 is behind the side 107 of the first spring102 as illustrated in FIG. 15. If, on the other hand, the safety shieldmembers 52, 54, 56 have not been previously retracted, the leg 103 ofthe first spring 102 will initially be disposed in the release positionillustrated in FIGS. 12 and 13 (i.e. with the leg 105 of the secondspring 104 already abutting both the side 107 of the leg 103 and thestop projection 106A of the stop 106). Thus, when the obturator andcannula handles 20, 134 are detached, both the first and second springs102, 104 move to the left simultaneously since they are biased in thatdirection. Consequently, the locking mechanism 100 will move from theposition illustrated in FIG. 12 into the position illustrated in FIG.15.

Thus, it will be appreciated that regardless of the initial position ofthe first spring 102 (i.e. lock or release), the separation of theobturator handle 20 from the cannula handle 134 will always cause thelocking mechanism 100 to move into the second locked positionillustrated in FIG. 15. Consequently, the locking mechanism 100 preventsthe safety shield members 52, 54, 56 from retracting whenever theobturator 12 and cannula 130 are separated. However, when the obturatorhandle 20 is re-attached to the cannula handle 134, the elongated leg114 of the translatable arm 108 contacts the cannula handle 134 and,thus, moves the translatable arm 108 and the adjacent second spring 104back to the right and into the position illustrated in FIG. 12. Sincethe second spring 104 abuts the side 107 of the leg 103 of the firstspring 102, the leg 105 forces the leg 103 to translate into its releaseposition. Thus, the locking mechanism 100 minimizes the risk of injuryby insuring that the piercing tip 16 can only be exposed when the trocar10 is completely assembled for use in a surgical procedure.

In use, the physician or surgeon first inserts the obturator 12 into thecannula 130. Prior to connecting the obturator handle 20 and the cannulahandle 134, the locking mechanism 100 is in the position illustrated inFIG. 15. In other words, the translatable arm 108 and the leg 105 of thesecond spring 104 are in their leftmost position and the leg 103 of thefirst spring arm 102 is in the lock position. When the obturator handle20 and cannula handle 134 are first assembled into a single handpiece14, the translatable arm 108, the leg 105 of the second spring 104 andthe leg 103 of the first spring 102 move into the position illustratedin FIG. 12 as explained above. Thus, the leg 103 of the first spring arm102 moves to the release position such that the safety shield members52, 54, 56 are free to move into the retracted position illustrated inFIG. 11.

The physician then places the shielded piercing tip 16 against thepatient's body wall and begins to apply force to the trocar 10. When theforce applied by the physician exceeds the biasing force of shieldspring 90, the safety shield members 52, 54, 56 retract into the shaft18 exposing the piercing tip 16 of the obturator 12. As illustrated inFIG. 12A, the movement of the safety shield members 52, 54, 56 causesthe first spring 102 and the leg 103 to translate with the attachmentblock 76 past the stop 106, thereby disengaging from the leg 105 of thesecond spring 104. As the piercing tip 16 passes into the patient's bodycavity and the safety shield members 52, 54, 56 return distally towardsthe extended position, the first spring 102 and the leg 103 move forwardcontacting the leg 105 of the second spring 104.

As the first spring 102 moves forward under the force of shield spring90, the leg 103 of the first spring 102 displaces the leg 105 of thesecond spring 104 away from the stop projection 106A of the stop 106. Asillustrated in FIG. 14, the relative positions of the first and secondsprings 102, 104 are thus reversed. The leg 103 of first spring 102 nowabuts the side of the leg 105 of the second spring 104 rather than viceversa. Accordingly, the leg 105 of the second spring 104 can no longerprevent the leg 103 of the first spring 102 from moving into the lockposition. Consequently, the leg 103 of the first spring 102 moves intothe lock position adjacent stop projection 106A but under the largestportion of stop 106 thereby locking the safety shield members 52, 54, 56in the extended position and preventing further retraction.

If the physician wishes to re-arm the trocar 10 so that the shieldmembers 52, 54, 56 can once again retract, the physician must repeat theabove described process. In other words, the physician must first detachthe obturator handle 20 from the cannula handle 134 such that thelocking mechanism 100 translates into the position illustrated in FIG.15. Then, the physician must re-attach the handles 20, 134 to return thelocking mechanism 100 to the position shown in FIG. 12 wherein the leg103 of the first spring 102 is once again free of the stop 106.

Other than the features of the attachment assembly 24 and lockingmechanism 100 explained above (i.e. notches 30, 32, and lead-in ramps116), the cannula 130 includes the standard cannula features known inthe art. Specifically, the cannula 130 is provided with an open-endedtube 132 which communicates with a cannula handle 134 for receivingsurgical instruments and the like during a surgical procedure. Inaddition, as illustrated in FIG. 8, the cannula handle 134 includes anopening 138 for receiving the surgical instruments which are passedthrough the interior of the handle 134 and the open-ended tube 132. Inorder to prevent the inert gas which is often used to inflate apatient's body cavity in a surgical procedure from escaping aroundinserted surgical instruments, the cannula opening 138 is provided withan annular seal 140. This seal 140 abuts the outer diameter of insertedinstruments thereby minimizing the amount of gas leakage.

As illustrated in FIG. 12A, the cannula 130 is additionally providedwith a spring loaded sealing flap 150 which prevents gas from escapingwhen the cannula 130 is not carrying an instrument or obturator 12 as isknown in the art. This sealing flap 150, which is disposed within thecannula handle 134, is preferably biased into contact with the opening138 by a torsion spring 152 such that the flap 150 blocks the opening138 and prevents gas from leaking when the cannula tube 132 is empty.

Finally, as illustrated in FIG. 8, the cannula 130 is also provided witha valve 142 for inflating and deflating the body cavity. The operationand construction of the valve 142, like the other standard features ofthe cannula 130, is well known in the art and, thus, need not bedescribed in detail here. Instead, it is sufficient to note that a tubecarrying pressurized gas from an external gas source can be affixed tothe valve 142 and the valve 142 can be opened and closed to permit adesired amount of gas to enter the body cavity for inflation. On theother hand, the valve 142 can be attached to a hose and opened todeflate the cavity and drain the gas into a container.

Some of the components of the trocar 10 such as the valve 142 arecommercially available products. Since these components are well knownin the art, there is no need to discuss specific techniques formanufacturing them here. Many of the other components such as theobturator handle 20, the safety shield members 52, 54, 56, theattachment block 76, the cannula tube 132, and the cannula handle 134are preferably constructed from molded plastic using standard moldingtechniques which are well known in the art. Finally, the seals 140 andsprings 90, 102, 104, 34, 152 mentioned above are all constructed usingmanufacturing techniques which are well known in the art. However,spring 90 is preferably made of 302 stainless steel and constructed togenerate spring forces between 0.3 lbs. and 1.6 lbs; spring 102 ispreferably made of 301 stainless steel and constructed to generateforces of approximately 1.3 lbs.; spring 104 is preferably made of 301stainless steel and constructed to generate forces in an axial direction(i.e. co-axially with the shaft) of approximately 0.08 lbs.; spring 34is preferably made of 301 stainless steel and constructed to generatespring forces of approximately 0.22 lbs.; and torsion spring 152 ispreferable made of 302 stainless steel and constructed to generatespring torques between 0.12 in-lbs. when the flapper door is closed and0.6 in-lbs when the flapper door is open. It will be appreciated,however, that although springs generating forces as noted above arepreferred, springs exhibiting other force generating characteristicsmight likewise be appropriate.

The multi-chambered obturator shaft 18 and integrally formed piercingtip 16, can be constructed by first extruding aluminum through a die ofan appropriate shape to form a multi-chambered tube. The extrudedaluminum may then be cut into workpieces of any desired length. One endof the workpiece can then be sharpened to form a piercing tip.Specifically, the shaft 18 can be sharpened by grinding, planing orotherwise cutting the side 19 and inner walls 40, 42, 44 of the shaft18. Referring to FIGS. 10A, 10B and 10D, a first cut would be made at anangle to the outer wall 19 thereby forming beveled portion 63 andopening 46. A second cut would be made at substantially the same angleto the outer wall 19 but oriented to form beveled portion 61 and opening48. The combination of these first two cuts would create the sharp blade41 between openings 48 and 46. A third and final cut would then be madeon the side opposite that illustrated in FIG. 10D. This final cut wouldcreate beveled portion 65 and two sharp blades 43 and 45. Triangularlands 51, 53, and 55 could then be formed by grinding, milling orturning the blades 41, 43, and 45 until they have the appropriatelengths. The completed shaft 18 can then be assembled with the otherdescribed components of the obturator 12. As previously mentioned, theremainder of the trocar components can be manufactured with molding andtooling techniques which are well known to those skilled in the art.

A cannula converter 210 constructed in accordance with the teachings ofthe present invention is shown generally in FIG. 16. As illustrated inFIG. 17, the cannula converter 210 is constructed for use with the abovedescribed cannula 130. As mentioned above, the cannula 130 includes anannular seal 140 for surrounding the exterior of surgical instrumentswhich have been inserted into the cannula 130. However, if a surgeonwishes to employ a surgical instrument having an exterior diametersmaller than the interior diameter of the cannula tube 132, a gap canexist between the annular seal 140 and the surgical tool. Such a gap canpermit gas to escape from the patient's body cavity. The cannulaconverter 210 overcomes this problem by operatively decreasing the innerdiameter of the cannula 130.

As illustrated in FIG. 25, the cannula converter 210 includes a housinghaving two interlocking components, namely, a seal housing or firsthousing component 211, and an attachment housing or second housingcomponent 213. As shown in FIG. 16, the seal housing 211 includes a topportion 212 defining an opening 214 adapted for receiving surgicalinstruments. An annular seal 240 similar to the annular seal 140contained in the cannula handle 134 is disposed within the opening 214.The annular seal 240 of the cannula converter 210 preferably has asmaller interior diameter 219 than the seal 140 of the cannula 130.Thus, the annular seal 240 of the cannula converter 210 can receivesurgical instruments with smaller diameters than the annular seal 140 ofthe cannula 130 and still prevent gas from escaping from the inflatedbody cavity.

Preferably, the area of the top portion or side 212 surrounding theopening 214 is molded into a smooth concave depression 215 asillustrated in FIG. 18. This depression 215 acts as a lead-in and visualtarget for inserting surgical instruments. In addition, the depression215 enables the surgeon to insert surgical instruments further into thebody cavity than would otherwise be possible.

As shown in FIG. 19, the bottom portion or side 216 of the attachmenthousing or second housing component 213 also defines an opening 218.This opening 218 is aligned with the opening 214 of the seal housing 211such that instruments passing through the top opening 214 can also passdirectly through the bottom opening 218. Further, the bottom portion 216of the attachment housing 213, like the top portion 212 of the sealhousing 211, includes a concave depression 217 around the opening 218.However, the bottom opening 218 is not provided with a seal.

Moreover, as illustrated in FIG. 20, the opening 218 in the bottom side216 of the attachment housing 213 is surrounded by an outwardlyprojecting rim or lip 220. When the cannula converter 210 is connectedto a cannula 130, this outwardly projecting rim 220 firmly abuts theannular seal 140 of the cannula handle 134 to form a seal which inhibitsgas leakage between the cannula 130 and the converter 210.

As illustrated in FIG. 24, the seal housing 211 and the attachmenthousing 213 combine to form a sealed channel 250 for passing surgicalinstruments between the top and bottom openings 214, 218. As shown inFIGS. 23 and 24, the bottom portion 252 of the seal housing 211 includesan inwardly projecting wall 254 defining an open-ended channel 256. Thisopen-ended channel 256 communicates with the opening 214 in the topportion 212 of the seal housing 211. However, the interior diameter ofthe open-ended channel 256 is slightly larger than the interior diameterof the opening 214. Consequently, the annular seal 240, whose outerdiameter preferably closely matches the inner diameter of the open-endedchannel 256, preferably rests adjacent the opening 214 against anannular ledge 223. This annular ledge 223 prevents the seal 240 frompassing through the opening 214.

As illustrated in FIG. 22, the top portion 260 of the attachment housing213 also includes an inwardly projecting wall 262. However, unlike theseal housing 211, the attachment housing 213 is also provided with asecond inwardly directed wall 264. The second wall 264 is concentricallyaligned with the first wall 262 and is preferably spaced from the firstwall 262 by spacers 268. Further, the second wall 264 defines anopen-ended channel 266 which communicates with the opening 218 in thebottom portion of the attachment housing 213. The outer diameter of thefirst wall 262 of the attachment housing 213 is slightly smaller thanthe inner diameter of the inwardly projecting wall 254 of the sealhousing 211. Consequently, the walls 262, 264 of the attachment housing213 are insertable into the inwardly projecting wall 254 of the sealhousing 211 as illustrated in FIG. 24. Thus, when the seal andattachment housings 211, 213 are assembled, the inwardly projectingwalls 262, 264 of the attachment housing 211 extend into the open-endedchannel 256 of the seal housing 213 to form a single sealed channel 250running between the openings 214, 218 of the seal and attachmenthousings 211, 213, respectively.

In the preferred embodiment, the inwardly projecting walls 262, 264 ofthe attachment housing 213 extend completely through the open-endedchannel 256 of the seal housing 211 to compress the annular seal 240firmly against the annular ledge 223 described above. The compression ofthe annular seal 240 prevents gas leakage from the sealed channel 250.

In order to attach the cannula converter 210 to the cannula 130, thecannula converter 210 is provided with an attachment device 224 which isvery similar to the attachment device 24 described above in connectionwith the obturator 12. Thus, as illustrated in FIG. 25, the attachmentdevice 24 includes two oppositely disposed pivotable buttons 227, 229and a button spring 234. The pivotable buttons 227, 229 each include atabbed arm 226, 228 and are disposed on opposite sides of the cannulaconverter 210 as illustrated in FIGS. 20, 21, 22 and 24. These tabbedarms 226, 228 engage the notches 30, 32 in the cannula handle 134 in thesame manner as the tabbed arms 26, 28 of the pivotable buttons 27, 29 ofthe attachment device 24 employed by the obturator 12. Thus, the buttonspring 234 is positioned adjacent the tabbed arms 226, 228 and biasesthe arms outward as illustrated in FIG. 22. By exerting an inwardlydirected force sufficient to overcome the biasing force of the buttonspring 234, the physician can disengage the arms 226, 228 from thenotches 30, 32 and remove the converter 210 from the cannula 130.

However, whereas the pivotable buttons 27, 29 of the obturator 12 werepivotally mounted on posts 25, 31, the pivotable buttons 227, 229 of thecannula converter 210 include integrally attached posts 225, 231.Further, these posts 225, 231 are each pivotally seated upon a pair ofcarriages 237, 239, respectively. As illustrated in FIG. 25, thesecarriages 237, 239 include rounded seats 238 which permit the buttonposts 225, 231 to rotate. In order to insure these posts 225, 231 remainfirmly seated during their rotations, the bottom 252 of the seal housing211 is provided with four pads 236 as shown in FIG. 23. Each of thesepads 236 is positioned directly above a rounded carriage seat 238. Whenthe converter 210 is assembled, these pads 236 abut the posts 225, 231of the buttons 227, 229 thereby permitting the posts 225, 231 to rotateupon the carriages 237, 239 while preventing them from becomingdislodged.

Most of the components of the cannula converter 210 are preferablyconstructed from plastic using molding techniques which are well knownin the art. However, the button spring 234 is preferably constructedfrom 302 stainless steel using manufacturing techniques which are wellknown to those skilled in the art. Further, although the spring 234preferably generates forces of approximately 0.7 lbs., springs of otherstrengths could also be used without departing from the invention.

A site stabilizer 310 constructed in accordance with the teachings ofthe present invention is shown generally in FIG. 26. As previouslymentioned, trocar cannulas such as the cannula 130 discussed above areoften provided with a smooth exterior surface to facilitate insertioninto a patient and to avoid excessive trauma to the flesh surroundingthe incision. However, this ease of insertion typically also means thatthe cannula 130 can be inadvertently removed from the patient whenwithdrawing instruments such as the obturator 12. As illustrated in FIG.27, the site stabilizer 310 overcomes these problems by providing athreaded exterior for the cannula 130 which can be used to grip thepatient's flesh and prevent accidental withdrawals.

As illustrated in FIGS. 26 and 30, the site stabilizer 310 is providedwith a stem 320 defining an open-ended channel 322 for receiving thecannula 130. In order to attach the cannula 130 to a patient's bodywall, the stem 320 of the site stabilizer 310 includes external threads324 which surround the cylindrical stem 320 and can be screwed into apatient's body wall. When threaded into a patient in this manner, thesite stabilizer 310 can be withdrawn by reverse threading the threads324 out of the incision. In order to facilitate the insertion of thestem 320 into the incision, the bottom of the stem 320 is tapered. Thistapered portion 323 provides a smooth transition between the cannula andthe site stabilizer as illustrated in FIG. 27.

As illustrated in FIG. 30, the site stabilizer 310 is further providedwith a head 330. When the site stabilizer 310 is fully threaded into abody wall, the head 330 abuts the patient's skin to prevent thestabilizer 310 from passing completely into the body cavity. Preferably,the head 330 has a flattened shape which permits the cannula 130 topenetrate nearly as far into the patient as it would otherwise havereached. The broad, flattened shape of the preferred head 330 alsoprovides a large surface for the physician to grip when threading thestabilizer into or out of the patient. To this end, the head 330 of thestabilizer 330 is further provided with a contoured finger notch 332 asshown in FIGS. 28 and 29. This finger notch 332 provides a secureresting point for the physician's thumb or other digit when gripping thestabilizer head 330 thereby avoiding the slipping problems that could beassociated with a completely round head and providing a secure grippingsurface for the physician when activating the handle 386 as described indetail below.

As illustrated in FIG. 33, the head 330 preferably comprises two parts,namely, a top portion 340 and a bottom portion 350. As shown in FIGS. 31and 32, the top portion 340 and the bottom portion 350 of the head 330each include an outer rim 343, 353. The top and bottom rims 343, 353,which project in opposite directions, are sealed together as illustratedin FIGS. 30 and 34 such that the flattened head defines an interiorchamber.

As shown in FIG. 28, the top portion 340 of the head 330 defines anopening 342 which is concentrically aligned with the open-ended channel322 defined by the stem 320. Thus, the cannula 130 can pass directlythrough the opening 342 and into the stem 322. Preferably, the area ofthe top portion 340 surrounding the opening 342 is molded into a smoothconcave depression 344. This depression 344 acts as a lead-in ramp toguide the cannula 130 into the site stabilizer 310 during insertion. Inaddition, the depression 344 serves the same purpose as the flattenednature of the head 330 itself. Specifically, it enables the surgeon toinsert the cannula 130 further into the body cavity than would otherwisebe possible.

As shown in FIG. 33, the bottom portion 350 of the head 330 also definesan opening 352 which is concentrically aligned with the opening 342 ofthe top portion 340 and the open-ended channel 322 defined by the stem320. Thus, when the site stabilizer 310 is attached to a cannula 130,the cannula 130 passes through both openings 342, 352 of the flattenedhead 330, and the open-ended channel 322.

In order to prevent gas from leaking from the patient's body cavitythrough the site stabilizer 310, the site stabilizer 310 is furtherprovided with an annular sealing ring or O-ring seal 360. As illustratedin FIG. 33, this annular sealing ring 360 is disposed in an annulardepression 354 in the bottom portion 350. Thus, when a cannula 130 isinserted through the openings 342, 352 of the head 330, the sealing ring360 grips the cannula's exterior thereby limiting gas leakage throughthe open-ended channel 322. The O-ring seal 360 also provides drag onthe cannula 130 to hold the position of the site stabilizer 310 when thetrocar 10 is being inserted.

In order to secure the site stabilizer 310 to the cannula 130, the sitestabilizer is further provided with a camming structure 370, atranslatable handle 380, and a gripping device 390 all disposed at leastpartially within the interior of the head 330. As illustrated in FIG.33, the camming structure 370 preferably comprises three upwardlyprojecting ramps 372 radially disposed around the opening 352 in thebottom portion 350 of the head 330. Each of these ramps 372 preferablyincludes an inclined portion 374 angling upwards from the bottom portion350 of the head 330 and a flat portion 376 attached to the inclinedportion 374. However, it will be appreciated by those skilled in the artthat other ramp structures having other numbers of ramps or rampswithout flattened portions 376 could likewise be employed.

The translatable handle 380 preferably includes a central hub 382concentrically aligned with the openings 342, 352 and channel 322 andhaving a central opening 383 through which the cannula 130 passes, threeradially projecting structures or projections 384 attached to thecentral hub 382 for operatively engaging the camming structure 370, anda manually engageable elongated arm 386. The elongated arm 386 of thetranslatable handle 380 extends through an opening 387 in the bottom rim353 of the head 330 as illustrated in FIGS. 33, 34 and 35. Thus, theelongated arm 386 can be manually translated between a release positionand a grip position.

In the release position illustrated in FIG. 31, the radially disposedprojections 384 are each disposed upon the bottom portion 350 of thehead 330 immediately adjacent an inclined portion 374 of a ramp 372 ofthe camming structure 370. However, as the elongated arm 386 istranslated towards the grip position, the radially projecting structures384 each engage an inclined portion 374 of a ramp 372 of the cammingstructure 370 and move upwards towards the flattened portions 376. Thistranslation up the ramps 372 of the camming structure 370 elevates thecentral hub 382 of the translatable handle 380 with respect to the head330 such that the hub 382 engages the gripping device 390.

As illustrated in FIG. 32, the gripping device 390 is preferablyfriction fit into a downwardly projecting, circular wall 345 attached tothe interior of the top portion 340 of the head 330. Thus, the grippingdevice 390 is suspended directly above the central hub 382 of thetranslatable handle 380. Further, as illustrated in FIG. 33, thegripping device 390 preferably comprises an annular ring 392 including aplurality of radially spaced, inwardly directed projections 394 whichtranslate between a first and a second position. In the first position,the inwardly directed projection are directed downward at a first angle,preferably at approximately a 450 angle from the annular rim 392. Whenthe central hub 382 abuts the gripping device 390, it forces theinwardly directed projections 394 upwards from the first positionillustrated in FIG. 35 into the second position illustrated in FIG. 34.This upward translation causes the projections 394 to extend furthertowards the center of the annular rim 392. Thus, the upward movement ofthe central hub 382 effectively decreases the inner diameter of thegripping device 390.

As shown in FIGS. 34 and 35, the cannula 130 passes through the centerof the gripping device 390. Consequently, when the inner diameter of thegripping device 390 is effectively reduced by the upward movement of theinwardly directed projections 394, the gripping device 390 firmly gripsthe cannula 130 as shown in FIG. 34. Thus, the movement of thetranslatable handle 380 from the release position to the grip positionforces the site stabilizer 310 to firmly grip the cannula 130. When thehandle 384 is translated back to the release position, the projections394 will return to their original position thereby releasing the cannula130 from the site stabilizer 310 as shown in FIG. 35.

In order to control the movement of the translatable handle 380, the topportion 340 of the head 330 is provided with a camming structurepreferably comprising downwardly extending ramps 347 as shown in FIG.32. Preferably, these downwardly extending ramps 347 are disposedadjacent the ramps 372 of the bottom portion 350 of the head 330. Theoppositely disposed ramps 347, 372 thus combine to define boundedchannels for guiding the radially projecting structures 384 as they movebetween the release and lock positions as illustrated in FIG. 30.

Although other materials and construction techniques might likewise beappropriate, most of the components of the site stabilizer 310 areconstructed from plastic using molding techniques which are well knownin the art. However, the O-ring seal 360 is preferably constructed fromsilicon using common production techniques which are well known to thoseskilled in the art. Even more preferably, the silicon used to constructthe O-ring seal 360 is the silicon sold under the product name"Baysilone" by Miles Inc. of Pittsburgh, Pa. 15205-9741.

Although the invention has been described in connection with certainembodiments, there is no intent to limit the invention to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents included within the spirit and scope ofthe invention as defined by the appended claims.

What is claimed is:
 1. A cannula converter for converting the sealingdiameter of a cannula, said cannula having an handle and an open endedtube defining a channel for receiving surgical instruments, said cannulaincluding a first seal having a first aperture, said first seal beingmounted within said cannula about said channel for sealing said channelby engaging a first diameter surgical instrument to maintain inflationof an inflated body cavity, said cannula converter comprising:acartridge unit having a top and a bottom with said top and bottom havingconcentric openings defining an instrument passage through saidcartridge unit for receipt of a second diameter surgical instrument,said second diameter surgical instrument having a diameter that issmaller than the diameter of said first diameter surgical instrument;said cartridge unit being adapted to be engaged and subsequentlyremovable from said handle such that said concentric openings areconcentric with said channel of said cannula such that said seconddiameter surgical instrument can be inserted through said cannula intoan inflated body cavity; a second seal having a second aperture which issmaller than said first aperture, said second seal being mounted withinsaid cartridge unit about said instrument passage for sealing saidpassage by engaging said second diameter surgical instrument to maintainthe inflation of an inflated body cavity; an attachment assembly forattaching the cartridge unit to the cannula such that surgicalinstruments can be passed through the channel of the converter and thecannula for performing surgical procedures without deflating an inflatedbody cavity; whereby, said cannula converter can be attached to acannula adapted for a first diameter surgical instrument and beconverted to receive a smaller second diameter surgical instrument.
 2. Acannula converter as defined in claim 1 wherein the attachment assemblyfurther comprises two oppositely disposed pivotable buttons pivotallymounted upon posts secured within the cartridge unit, each of thepivotable buttons being manually engageable from outside the cartridgeunit for movement between a lock position and a release position, andeach of the pivotable buttons including tabbed arms extending out of thecartridge unit for operatively engaging a cannula when the buttons arein the lock position.
 3. A cannula converter as defined in claim 1,wherein said bottom of said cartridge unit has an outwardly projectinglip that is adapted to firmly abut the channel in the cannula handle. 4.A cannula and converter for converting for converting the sealingdiameter of the cannula comprising:a cannula having a handle and an openended tube defining a channel for receiving surgical instruments, saidcannula including a first seal having a first aperture, said first sealbeing mounted within said cannula about said channel for sealing saidchannel by engaging a first diameter surgical instrument to maintain theinflation of an inflated body cavity; a cartridge unit having a top anda bottom with said top and bottom having concentric openings defining aninstrument passage through said cartridge unit for receipt of a seconddiameter surgical instrument, said second diameter surgical instrumenthaving a diameter that is smaller than the diameter of said firstdiameter surgical instrument, said cartridge unit being adapted engagedand subsequently removable from said handle such that said concentricopenings are concentric with said channel of said cannula such that saidsecond diameter surgical instrument can be inserted through said cannulainto an inflated body cavity; a second seal having a second aperturewhich is smaller than said first aperture, said second seal beingmounted within said cartridge unit about said instrument passage forsealing said passage by engaging said second diameter surgicalinstrument to maintain the inflation of an inflated body cavity; anattachment assembly for attaching the cartridge unit to the cannula suchthat surgical instruments can be passed through the channel of theconverter and the cannula for performing surgical procedures withoutdeflating an inflated body cavity; and whereby, said cannula convertercan be attached to said cannula adapted for a first diameter surgicalinstrument and be converted to receive a smaller second diametersurgical instrument.